package com.jia.jianzhiOffer;

import java.util.ArrayList;

/**
 * 29.顺时针打印矩阵
 * 题目描述
输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，如果输入如下4 X 4矩阵： 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
 * 
 * @author Administrator
 *
 */
public class Pro29 {
    public ArrayList<Integer> printMatrix(int [][] matrix) {
        ArrayList<Integer> ret = new ArrayList<Integer>();
        if(matrix == null) return ret;
        int r1 = 0, r2 = matrix.length - 1, c1 = 0, c2 = matrix[0].length-1;
        while(r1 <= r2 && c1<=c2) {
            for (int i = c1; i <= c2; i++)
            ret.add(matrix[r1][i]);
        for (int i = r1 + 1; i <= r2; i++)
            ret.add(matrix[i][c2]);
        if (r1 != r2)
            for (int i = c2 - 1; i >= c1; i--)
                ret.add(matrix[r2][i]);
        if (c1 != c2)
            for (int i = r2 - 1; i > r1; i--)
                ret.add(matrix[i][c1]);
        r1++; r2--; c1++; c2--;
        }
        return ret;
    }
}
